Motional environments, segmented copolymers

The specific questions to be addressed by solid state deuterium NMR studies of this polymer are the following (1) Are the motions of the CD2 groups in the segmented copolymer identical to the motions observed in the poly (butylene terephthalate) homopolymer (2) What effect do variations in the hard soft content ratio have on the motions of the CD2 groups And (3), is there evidence for hard segments which reside in the soft segment matrix If so, what per cent of them are in non-poly (butylene terephthalate)-like environments ... 

The spectra shown in Figure 5 clearly indicate that there are two distinct motional environments in the segmented copolymers. The broad component of the spectrum arises from the majority of the hard segments which show motional characteristics similar to that of poly (butylene terephthalate). The sharp component is attributed to hard segments which reside in the soft segment matrix, either by virtue of being very short blocks, or because they form loops on the surfaces of the hard segment lamellae. 

The results presented here show that there are two distinct motional environments for the "central" deuterons of poly (butylene terephthalate) in the segmented copolyesters containing poly (butylene terephthalate) as the hard segment. One of the motional environments is identical to that observed in the poly (butylene terephthalate) homopolymer, in which Helfand-type motions (6) about three bonds occur with a correlation time of 7 x 10-6 s at 20 °C. The Tj for these deuterons is ca. 60 ms at 20 °C. Approximately 90% of the hard segments reside in these organized lamellar environments in the segmented copolymer with 0.87 mole fraction hard segments. 

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